Legal advice - can a lender settle a loan then ask for more money?

[Orinoco]

I recently took out a personal loan from a high street lender, as they had the lowest interest rate available.

I unexpectedly was able to repay this loan a lot faster than I intended, in fact about five weeks after I took it out. I phoned them for a repayment figure, which I queried as it seemed a bit high. The chap rechecked, and said that as I'd not yet had the DD collected, I could cancel the loan and just repay back the amount I borrowed plus a transfer of money fee.

I sent off a cheque for this amount and subsequently received a letter confirming my account had been paid in full and was now closed.

However, today I've had a letter stating that following an internal audit I've not paid enough to clear my balance, and they want another £64 off me.

Are they allowed to do this?

Thanks

They may have made a mistake, but they confirmed your account was clear, so I'd stick with that. Just write stating that, as far as you are concerned, your account is closed and no further monies are due. They could sue for the extra, but, if you produce their letter in court, it's highly unlikely you'd be on the losing side.